The present invention relates in general to the field of blank firing adapters and other low impulse firing adapters for automatic weapons. More specifically, the present invention relates to automatic weapons that feature a combination of gas and recoil operation.
Reduced cartridge impulses provided by lower mass projectile systems and/or reduced chamber pressure will result in reduced operating energy in the gun system. Consequently, the weapon cyclic rate will be reduced to the point of non-function. Exemplary low impulse cartridges that produce much lower impulse levels than required to function weapons in the fully automatic mode, include blanks, limited range training ammunition, and non-lethal cartridges. All of these cartridges have high value for training and non-lethal operations, and a mechanism of operating the weapon realistically whilst firing these low impulse munitions is highly desired.
There is a great and still unsatisfied seed for a low impulse firing adapter for use in a combination gas and recoil operated automatic weapon.
Blank cartridges, limited range training rounds, non-lethal cartridges and other low impulse cartridges will not function automatic weapons that rely on both ammunition recoil impulse and gas pressure. Combination gas and recoil operated weapons use gas pressure bled from the barrel during firing to power the gas system, while the ammunition recoil impulse provides the energy for recoil operation.
One feature of the present invention is to satisfy this long felt need by providing a low impulse adapter for use in a combination gas and recoil operated automatic weapon.
Another feature of the present invention is to provide an adapter configuration that accelerates the recoiling masses and at the same time provides a mechanism to pressurize the gas system. This allows for the launching of low velocity and or low mass projectiles such as a blank round while functioning combination gas and recoil operated weapons in the full automatic mode.
The present invention solves this problem by using a barrel insert that provides a mechanism for producing the necessary gas pressure at the gas port, while also providing a gas piston mechanism to force the recoiling masses rearward.
The present invention also provides a barrel insert or sleeve that allows the piston diameter to be smaller than the barrel bore diameter, in order to provide a force transmitted to the receiver below the level that would damage the receiver.
A further feature of the present invention, is to provide a fully automatic weapon function without requiring changes to the weapon itself, while permitting effective firing of reduced impulse munitions.
These and other features and advantages of the invention are achieved by a low impulse adapter and companion low cost blank ammunition. Projected savings associated with using low cost blank ammunition of the present invention in lieu of combat ammunition will be significant.
This invention also allows firing of low cost training cartridges, limited range training cartridges, non-lethal cartridges, and other reduced impulse/low impulse cartridges for combination gas and recoil operated weapons.
Two possible configurations of the blank cartridge are illustrated herein. One embodiment is comprised of a hollow assembly with forward crimp and contained within the cartridge proper is a commercial .44 caliber blank cartridge or similar small caliber cartridge that has been loaded with a primer and propellant charge to provide the pressure characteristics desired in adapter operation.
The second embodiment provides an equally effective configuration, and shows the cartridge envelop containing the propellant charge that provides the desired burning and pressure characteristics. This cartridge provides the exterior characteristics required to feed through the weapon and chamber prior to firing.
The adapter is comprised of a barrel insert that is firmly affixed to the weapon barrel. The barrel insert provides the mechanism for providing the gas pressure required at the gas port while allowing the use of a sub-caliber piston to recoil the barrel and recoiling mass. The sub-caliber piston allows the loads transmitted through the adapter to the weapon receiver to be held below the level at which damage to the receiver would occur.
The operation of one embodiment of a straight recoil version of a combination gas and recoil operated weapon using the adapter of the present invention is as follows: The blank cartridge travels through the weapon feed mechanism. The outside configuration of the cartridge and the position of the link are preferably constrained to that of conventional full service ammunition in order to be compatible with the weapon. The link and cartridge are restrained during the final feed operation in a ready to feed position. As the sear is depressed in firing, the main operating springs of the weapon accelerate the bolt and bolt carrier forward. The bolt strips the cartridge from the feed mechanism. The cartridge is then chambered within the barrel. The firing pin then engages the primer of the cartridge and ignition occurs.
Upon firing, gases are generated within the blank case and gases are expelled into the barrel assembly of the weapon. These gases are constrained by the barrel insert of the adapter which leads to a pressure build up within the barrel assembly. Gas is bled off of the barrel assembly through the gas port and is used to power the gas system.
The gas pressure delivers an equal and opposite net forward thrust on the sub-caliber piston and rearward thrust upon the locked barrel assembly, accelerating the barrel rearward and powering the recoil portion of the weapon function.
The sub-caliber piston within the adapter allows for the use of the relatively high gas port pressure while limiting the peak force transmitted through the adapter to the receiver. In one embodiment, a check valve within the barrel insert prevents the gas from bleeding back into the chamber and assures that gas pressure is maintained during piston operation and barrel recoil. This arrangement may also be used to allow the chamber pressure to be bled down prior to the cartridge case extraction.
The operation of a fire-out-of-battery version of a combination gas and recoil operated weapon using the adapter of the present invention is as follows: The blank cartridge travels through the weapon feed mechanism. The outside configuration of the cartridge and the position of the link are preferably, but not necessarily, constrained to that of conventional full service ammunition, in order to be compatible with the weapon mechanism. The link and cartridge are restrained during the final feed operation in a ready to feed position as the barrel, bolt, and carriage system are restrained to the rear ready to fire position by the weapon""s searing system. As the sear is depressed in firing, the operating springs of the weapon accelerate the barrel, bolt, and carriage assembly forward.
At a prescribed point, the bolt strips the cartridge from the feed mechanism. The cartridge is then chambered within the barrel. The barrel assembly then continues to accelerate forward until reaching the firing position. The firing pin then engages the primer of the cartridge and ignition occurs.
Upon firing, gases are generated within the blank case until such time as the gas pressure exceeds the crimping force of the cartridge. Gases are expelled into the barrel assembly of the weapon. These gases are constrained by the barrel insert and the piston of the adapter, which leads to a pressure build up within the barrel assembly. Gas is bled off of the barrel assembly through the gas port and is used to power the gas system. In so doing, the bolt is unlocked, the cartridge is extracted and ejected, and the bolt carriage is returned to the seared position.
The gas pressure delivers an equal and opposite net forward thrust on the sub-caliber piston and rearward thrust upon the barrel assembly delivering it fully to the rear or seared, ready to fire position. At this time the operating assembly is retained by the sear assembly or if burst firing is desired, the sear remains depressed and the weapon will continue to fire automatically until its fire is arrested by the operator or the weapon runs out of ammunition.
The sub-caliber piston within the adapter allows for the use of the relatively high gas port pressure while limiting the peak force transmitted through the adapter to the receiver. In one embodiment, a check valve within the barrel insert prevents the gas from bleeding back into the chamber and assures that gas pressure is maintained during piston operation and barrel recoil. This arrangement also allows the chamber pressure to be bled down prior to bolt unlock and cartridge case extraction.
An alternative embodiment of the present invention allows for the firing of sub-caliber projectiles such as low impulse non-lethal payloads or limited range training projectiles. Whilst these ammunitions would not normally function in combination gas and recoil operated weapons, this embodiment allows for a fully functional use of these munitions that have valuable training and tactical uses.
The present invention enables the practical and efficient use of low impulse ammunition in an unmodified combination gas and recoil operated weapon. This design is enabled by the ability of the present adapter system to use the same gas pressure within the barrel necessary to actuate the gas system whilst at the same time the adapter causes sufficient rearward thrust upon the recoiling parts to return the recoiling parts to the rear, sear position. The use of a barrel sleeve and sub-caliber piston allows the forces transmitted through the adapter to the receiver to be controlled and maintained at a practical level.